Refraction

-Refraction of Sound

-Refraction of Light

• Is it harder to push a lawn-mower on concrete or grass?

• Is it harder to walk through a pool full of water or air?

• Do you think that light waves also have a harder time going through water than air?

Refraction

Refraction• The change in direction of a wave as it

crosses the boundary between two media in which the wave travels at different speeds.

• Both light and sound waves change direction when they enter new media at angles greater than 0o.

Refraction of Sound• Sound waves are refracted when parts of a wave

front travel at different speeds.

• Do sound waves travel faster in warmer or colder air?

Refraction of Sound

Refraction of Light

Refraction of Light

• Light changes speed as it passes from one medium to another. This changes the directions of light rays.

Refraction of Light

• When light rays enter a medium in which their speed decreases, the rays bend toward the normal.

• When light rays enter a medium in which their speed increases, the rays bend away from the normal.

Index of Refraction and Snell’s Law

• Index of Refraction:

• Snell’s Law:

n = speed of light in vacuumspeed of light in material

n sin = n’ sin ‘